Respirator module with speech transmission and exhalation valve

ABSTRACT

A respirator speech transmitter and exhalation valve module comprising a resilient exhalation valve having a low airflow resistance for exhalation but providing a secure seal against inadvertent inhalation through the exhalation valve module. An exhalation airflow channel is formed between a module body on the outside of the channel and a conical airflow guide and the exhalation valve on the inside of the channel. The exhalation airflow channel is in the form of an amplification horn. The airflow channel produces a smooth airflow for unrestricted exhalation and high intelligibility of a user&#39;s speech. The module includes a drinking conduit for selectively fluidly connecting a mouthpiece in the respirator to a beverage container and further includes an electrical communication block with internal and external fittings for connecting a microphone in the mask to a radio or amplifier carried by the mask user.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Ser.No. 60/306,333, filed Jul. 18, 2001.

BACKGROUND OF INVENTION

1. Field of the Invention

The invention relates to a respirator with a module that includes aspeech transmission and exhalation valve functions. In one of itsaspects, the invention relates to a respirator module incorporating anexhalation valve, a speech transmitter and a drinking tube. In anotherof its aspects, the invention relates to a respirator speechtransmission module with integral electrical connections forcommunications devices. In another of its aspects, the invention relatesto a respirator with a speech transmission and an exhalation valvemodule. In yet another of its aspects, the invention relates to arespirator and speech transmitter module therefore with low airflowresistance through the module.

2. Description of the Related Art

When a respirator such as a gas mask is used in a contaminatedenvironment, it is critical that the wearer only inhale air from apurified source or air that has been passed through a filtrationcanister. In the typical gas mask having removable filtration canisters,the filtration canisters are attached to a filter mount including aninhalation valve that provides for one-way flow, opening duringinhalation and closing during exhalation to prevent exhalation of hot,moisture-laden air through the filter.

It is important that the inhalation valve introduce no restrictions inthe airflow path that will put additional strains on the wearer. In likefashion, it is important that an exhalation valve has minimalrestrictions in the exhalation airflow but has secure sealing duringinhalation. As the inhalation valve must have a low-opening pressure,the exhalation valve must also have a low-opening pressure to reduce theburden on the wearer and the likelihood of breaking the seal of therespirator.

Further, it is important that the wearer has the ability to communicateclearly with others in the vicinity or by radio while the respirator isin place and functioning in the contaminated environment. It istherefore advantageous for an exhalation module to have low-resistanceopening during wearer exhalation, complete sealing during wearerinhalation and with high intelligibility of wearer speech.

U.S. Pat. No. 4,958,633, issued Sep. 25, 1990, to Angell, discloses arespirator with a speech and exhalation module incorporating anelastomeric exhalation valve. The exhalation valve is constructed ofresilient material in a generally dished form anchored at a centralportion and adapted to seal on a peripheral edge onto a valve seat onthe module housing. The exhalation valve has an annular channel, formedby an annular arcuate section and that faces the outside of the mask.The module forms an air path in the form of an exponential horn betweenthe inside and outside of the mask. The air path reverses axialdirection between the inlet and the outlet, creating some turbulence.The speech module and exhalation valve have a fairly low resistance toexhalation, in the range of about 15 mm at 85 l/min air flow. Therespirator also has interchangeable mountings on the face piece for asecondary speech outlet, such as a microphone, and for an air-purifyingcanister. The speech transmitter module is disclosed more fully in theU.S. Pat. No. 4,539,983, issued Sep. 10, 1985, to Angell. These twoAngell patents are incorporated herein by reference in their entirety.

SUMMARY OF THE INVENTION

The invention relates to a respirator and a front module therefor as setforth in the preamble to claim 1 and wherein the inner side wall of themodule body forms with the airflow guide an airflow channel in the formof a horn expansion contour during exhalation when the outlet valve isin an open position. The airflow channel from the interior to theexterior of the module extends radially and axially outwardly, thenbends radially inwardly and axially outwardly through a smooth curve andthen bends through a smooth curve axially outwardly. The airflow patterndoes not reverse direction and thus has a very low resistance. In oneembodiment, the outlet valve forms a part of the airflow channel withthe inner side wall of the module body.

In one embodiment, the form of the horn expansion is conical,exponential, hyperbolic, tractrix or a combination thereof. In apreferred embodiment, the airflow guide has a generally conical surfacefacing the outer face of the module. In addition, the airflow guideconical surface is concave and the airflow guide has a relatively flatbottom surface facing the inner face of the module. An outer edge of theexhalation valve abuts the bottom surface of the airflow guide when theexhalation valve is in the open position. In one embodiment of theinvention, the bottom surface of the airflow guide has relief channelsto prevent sticking of the exhalation valve in the open position.

The invention also relates to a respirator and a front module thereforas set forth in the preamble to claim 1 and wherein the outlet valve hasa dome shape with a central body and a generally conical skirt. In oneembodiment, the outlet valve conical skirt is slightly convex outwardlytoward the outer face of the module body. Further, the outlet valvefurther has convex shoulder hinge between the central body and theconical skirt to toggle the outlet valve between an open position and aclosed position. Still further, the convex shoulder hinge forms achannel that opens toward the inner face of the module body.

The invention further relates to a respirator and a front moduletherefor as set forth in the preamble to claim 1 and wherein the modulefurther includes an electrical communication block with internal andexternal fittings for connecting a microphone in the mask to a radio oramplifier carried by the mask user.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a front view of a respirator with a respirator speechtransmitter and exhalation valve module according to the invention.

FIG. 2 is a partial cross-sectional view in perspective taken throughline 2-2 of the respirator speech transmitter and exhalation valvemodule of FIG. 1;

FIG. 3 is a perspective view of the outside of the speech transmitterand exhalation valve module shown in FIGS. 1 and 2 with portions of theouter surface removed for illustration of the interior of the module.

FIG. 4 is a plan view of the inner face of the respirator speechtransmitter and exhalation valve module of FIGS. 1-3.

FIG. 5 is a cross sectional view taken along lines 5-5 of FIG. 4

FIG. 6 is a cross-sectional view taken through line 6-6 of FIG. 2.

FIG. 7 is a cross-sectional view in perspective of the domed outletvalve used in the respirator speech transmitter and exhalation valvemodule of FIGS. 1-6.

FIG. 8 is a partial enlarged view of a drinking tube valve of therespirator speech transmitter and exhalation valve module of FIGS. 1-7.

FIG. 9 is a cross-sectional view taken through line 9-9 of FIG. 8.

FIG. 10 is a cross-sectional view taken through line 10-10 of FIG. 8with the drinking tube valve in the closed position.

FIG. 11 is a cross-sectional view like FIG. 10.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the drawings and to FIG. 1 in particular, a gas mask orrespirator assembly 310 comprises a mask 312 having a facepiece 330 thatfits onto a user's face and defines an interior chamber, a visor 332comprising a transparent polyurethane panel 336, or panels, that may ormay not have a central elastomeric hinge 338, a pair of circular orelliptical filter canisters 314 each mounted to the mask 312 at acanister mount 313.

Facepiece 330 is held to a user's face by a plurality of low-profileharness straps 344 defining a seal at facepiece periphery 334 thateliminates hot spots and fits comfortably with a helmet. Harness straps344 can be folded over the exterior of facepiece 330 to aid user inrapidly donning mask 312. The interior chamber of mask 312 furthercomprises a nose cup (not shown) that is formed of a suitable materialsuch as silicone or polyisoprene and is provided in multiple sizes forcomfort and fit on different users.

The canister mounts 313 each include an inlet port and self-sealingmechanism assembly 316 and a connector 318 for affixing the circular orelliptical filter canisters 314 to mask 312.

The assembly 310 further comprises a front module 10 that includesspeech transmission and exhalation valve functions affixed to mask 312.Module 10 combines and integrates the functions of speech, drinkingsystem, outlet valve assembly and electrical communication.

Referring now to FIGS. 2-7 in particular, front module 10 includes amodule body 12 having an inner face 14, an outer face 16 and a centralcavity 18 defined by a smooth and continuous side wall. A conicalairflow guide 30 is supported within the cavity 18 by a number ofairflow guide struts 32 that are connected to the airflow guide 30 andto the side wall of the central cavity 18 to hold the conical airflowguide substantially centered within the central cavity 18. The conicalairflow guide has a concave upper surface 33 and a relatively flat lowersurface. The module body 12 further includes a peripheral shoulder 80having a facepiece engaging surface 82 for mounting the module 10 to thefacepiece 312 of a respirator (FIG. 1). A skirt 84 extending from theperipheral shoulder 80 is mounted in a conforming opening in a facepieceadapted to receive the speech transmitter module 10. The skirt 84includes a circumferential bead 86 for assisting in retaining the module10 in the facepiece opening and further provides a retention means for anosecup within the respirator facepiece.

The central cavity 18 provides a flow path, illustrated by the arrows inFIG. 5, between an inlet opening 50 at the inner face 14 of the mask toan outlet opening at the outer face 16 of the mask through slots 44. Theouter face 16 of the module body 12 includes a plurality of slats 40defining an outer face grille 42. The slats 40 are not shown in FIG. 3so that the conical airflow guide 30 can be seen in the cavity 18. Theair flows between the inside and outside of the module body 12 throughslots 44 defined between the slats 40 of the grille 42.

At the inner face 14 of the module body 12, the cavity 18 includes thesubstantially circular opening 50 defined by an annular valve seat 60for fluidly connecting the cavity 18 to the inner face 14 of the modulebody 12. The circular opening 50 is surrounded at the base of centralcavity 18 of the module body 12 by the annular valve seat 60.

An outlet valve attachment stud 52 is mounted to the annular valve seat60 in a central portion of the circular opening 50 through a pluralityof spokes 54. The valve attachment stud 52 and spokes 54 define a numberof airflow apertures 56 for fluidly connecting the cavity 18 to theoutside of the module body 12 at the inner face 16.

The side wall of the cavity 18 and the upper surface 33 of the conicalairflow guide 30 define the airflow channel 70 through the module body12 from the airflow apertures 56 at the inner face 14 of the module body12 to the slots 44 at the outer face 16 of the module body 12. Theairflow channel 70 defines a horn expansion contour that enhances thesound transmitted by a user through the speech module. The form of thehorn expansion can be conical, exponential, hyperbolic, tractrix or acombination of theses forms. As illustrated in FIG. 5, the airflowpattern between the airflow apertures 56 and the slots 44 follows asmooth, continuous route without any reversal of direction. The airflowpattern begins in a radial outward and axial direction and then bendssmoothly in a radially inward and axial outward direction and thensmoothly turns axially outwardly.

The outlet valve attachment stud ˜52 mounts a domed outlet valve 90. Thedomed outlet valve 90 includes a central cylindrical body 92 surroundedby an outwardly convex shoulder hinge 94 and an umbrella-like skirt 96having a ribbed, weighted perimeter 98. The skirt 96 is convex outwardlyslightly toward the outer face 16 of the module body 12. The shoulderhinge 94 forms an open channel of generally semi-circular cross-sectionand the channel opening faces the inside of the module and therespirator. The central cylindrical body 92 includes a stud-receivingcavity 100 adapted to closely receive the outlet valve attachment stud52.

The outlet valve attachment stud 52 is positioned centrally within thecircular opening 50 and directed into the cavity 18. The domed outletvalve 90 is configured such that with the outlet valve attachment stud52 received in the cavity 100 of the central body 92 of the domed outletvalve 90, the ribbed perimeter 98 of the domed outlet valve 90 issealingly received in the annular valve seat 60.

The domed outlet valve 90 is resilient and biased toward a closedposition with the perimeter 98 of the outlet valve 90 pressed againstthe annular valve seat 60 within the central cavity 18 of the modulebody 12 to form an airtight seal. This configuration eliminates thepossibility that the outlet valve 90 will be drawn inside out during aninhalation process. As the wearer exhales, the domed outlet valve 90rolls up the hinge 94 and then inverts so that it abuts the base 34 ofthe conical airflow guide 30. The convex shoulder hinge 94 functions asa rolling toggle mechanism to flip the valve very wide open at thelowest possible positive (exhalation) pressure and closing quickly whenthe exhalation pressure drops near zero. The domed or umbrella shape ofthe valve is designed such that more energy is stored in the valve wheninverted and this helps to revert the valve back rapidly to the closedposition. This rolling hinge action represents a major change overcone-shaped valves that have a tendency to be lazy and not to revert asrapidly. The opening and closing of the outlet valve 90 takes place veryquickly when the pressure changes from positive to negative. The harderthe work rate, the more rapid and deep is the pressure change as theairflow volume increases per breath. The valve 90 accommodates a widevariety of changes very quickly.

The base 34 of the airflow guide 30 is formed with a central depression36 and a series of radial relief channels 38. The relief channels orgrooves 38 prevent the skirt 96 of the outlet valve 90 from sticking tothe base 34 by surface tension from breath moisture and forming anairtight seal when the valve is forced up against the base duringexhalation.

The inverted outlet valve 90 cooperates with the conical airflow guide30 to create an unobstructed airflow channel 70 through the cavity 18 ofthe module body 12. Exhalation air (shown by arrows) flows from theinterior of the respirator through the airflow apertures 56 at the innerface 14 of the module body 12. The exhalation air then passes by theinverted outlet valve 90 and around the conical airflow guide 30,through the airflow channel 70, and through the slots 44 in the outerface 16 of the module body 12. Exhalation air in the form of speech bythe wearer passes through the airflow channel 70 in a like manner; theexpansion contour of the horn form of the airflow channel enhances theintelligibility of the wearer's speech.

The surfaces of the side wall of the cavity 18 and the skirt 96 of thedomed valve 90 at the inner portion of the module and the side wall ofthe cavity 18 and the upper surface 33 of the conical airflow guide 30define an expanding airflow channel in a smooth continuous horn patternbetween the airflow apertures 56 and the slots 44 to amplify the speechfrom the user and to minimize the flow resistance through the airflowchannel. The airflow through the airflow channel has very little, ifany, turbulence and yet has a very low dynamic leakage due to thesensitivity of the exhalation valve. The combination of the lowresistance domed valve 90 and the smooth, axially non-reversing andcontinuously expanding horn airflow passage walls minimize the airflowresistance through the airflow passage to a very low value. For example,it has been found that the flow resistance to airflow through theairflow channel 70 is a little as 6 mm water gauge at 85 l/min with theconfiguration illustrated in the drawings and described above.

As the wearer of the respirator completes his exhalation, the outletairflow rate decreases until it can no longer overcome the bias in theoutlet valve 90. The outlet valve 90 then returns to its naturallybiased position and forms a seal against the annular valve seat 60. Asthe wearer of the respirator inhales, the outlet valve 90 is firmlyseated in the annular valve seat 60 and prevents the infiltration ofinhalation air through the outlet airflow apertures 56.

The central cavity 18 is protected from the impingement of solid matterby the outer face grille 42. The domed outlet valve 90 is furthershielded from the outer face 16 of the module body 12 by the conicalairflow guide 30. The domed outlet valve 90 is not visible from theouter face 16 of the module body 12 through the outer face slots 44.

The respirator speech transmitter and exhalation valve module 10 furtherincludes a drinking tube storage channel 110 for storing a drinking tube120 on the exterior of the module 10. The drinking tube 120 has a distalend 122 for connecting to a fluid source such as a water bottle and aproximal end 124 for fluidly connecting to a drinking tube hole 130passing through the module body 12.

The drinking tube hole 130 is selectively sealed by a drinking tubevalve 140 shown in FIGS. 8-11. The drinking tube valve 140 includes ablind end hollow tube 142 having an activation tap lever 144 forplacement on the outside of the module body 12. The inner end 146 of thedrinking tube valve 140 is adapted for fitting a mouthpiece 148 enablinga wearer of a respirator to drink from the water bottle. The drinkingtube valve 140 includes an opening 150 in a side of the hollow tube 142for selectively fluidly connecting the mouthpiece 148 to the proximalend 124 of the drinking tube 120. The drinking tube 120 is secured on afitting 152 fluidly connected to the drinking tube hole 130. With thedrinking tube valve 140 in the closed position as shown in FIG. 9, thefitting 152 and drinking tube 120 are fluidly isolated from themouthpiece 148. When the drinking tube valve 140 is moved to the openposition as shown in FIG. 11, the hole 150 in the side of the tube 142is aligned with the fitting 152 to fluidly connect the drinking tube 130with the mouthpiece 148. As the drinking tube valve 140 is rotated fromthe closed to the open position, the mouthpiece 148 simultaneously movesfrom a stored position away from the wearer's mouth to a positionaccessible to the wearer.

The module body 12 further incorporates an integrally moldedcommunication connector block 160 for providing an electrical andcommunication connection between the inner and outer faces 14, 16 of themodule body 12. The connector block 160 is preferably integrally moldedwith the module body 12 and can be used for attaching a microphone (notshown) to internal terminal connectors 162 on the inner face 14 of themodule body 12. The microphone can be electrically powered with the useof all three terminal connectors 162 or unpowered with the use of onlytwo of the terminal connectors 162. A communications device, such as aradio or an amplifier (not shown) carried by the respirator user, can beconnected to the external terminal connectors 164 on the outer face ofthe module body 12. All three terminal connectors 164 can be used toconnect electrical power to the interior microphone. Alternatively, onlytwo of the terminal connectors 164 can be used to connect the radio oramplifier to an unpowered microphone. The connector block 160 is alsoprovided with an integrally molded connector block cover 166 forprotecting the external connectors 164 when not in use.

In use, the respirator speech transmitter and exhalation valve module 10provides an exhalation valve and airflow management for a respirator andprovides a conduit through which the wearer of the respirator canintelligibly speak. For face-to-face conversation the wearer's voice iscarried through the outlet airflow charmer 70. For electroniccommunication, the wearer's voice can be carried through the outletairflow channel 70 to an external microphone, or the wearer can use aninternal microphone electrically connected to the internal connectors162 with the electronic communication device electrically connected tothe external connectors 164. The module 10 provides pass-throughconnectors for a microphone and electronic communication. The module 10further provides an attachment location for the nose cup as part of theairflow management process. Still further, the module 10 incorporates adrink tube connection to the mask and provides a convenient parkingplace for the drink tube. The module 10 has a low dynamic leakage whilea very low flow resistance due to the smooth flow of the airflow throughthe air passage in the module.

While the invention has been specifically described in connection withcertain specific embodiments thereof, it is to be understood that thisis by way of illustration and not of limitation. Reasonable variationand modification are possible within the scope of the forgoingdescription and drawings without departing from the spirit of theinvention which is defined in the appended claims.

1. A respirator comprising a facepiece defining an interior chamber forfiltered air and including at least one inhalation opening for passageof filtered air from the atmosphere to the interior chamber; at leastone exhalation opening for passage of air from the interior chamber tothe atmosphere; and a filtration canister removably mounted to thefacepiece and in fluid communication with the at least one inhalationopening for passage of purified atmospheric air to the facepieceinterior chamber; a self-sealing valve mounted in the at least oneinhalation opening and adapted to seal the at least one inhalationopening to prevent inhalation of air therethrough when the filtrationcanister is removed from the facepiece and to open the at least oneinhalation opening to permit inhalation of air therethrough when thefilter canister is mounted to the facepiece; and a speech transmitterand exhalation valve module mounted in the at least one exhalationopening and adapted to seal the at least one exhalation opening toprevent inhalation of air therethrough and to open the at least oneexhalation opening to permit exhalation of air therethrough, the speechtransmitter and exhalation valve module comprising: a module body havingan inner face, an outer face and an outer wall; a airflow cavity definedby an inner side wall of the module body and extending between openingsin the inner and outer faces of the module for fluidly connecting theinner face and the outer face; an airflow guide positioned within thecentral cavity; and an outlet valve, mounted to the module body and inthe airflow cavity, and adapted to close and fluidly seal the airflowcavity during inhalation and to open during exhalation, characterized inthat: the inner side wall of the module forms with the airflow guide andthe outlet valve an airflow channel in the form of a horn expansioncontour during exhalation when the outlet valve is in an open position.2. A respirator according to claim 1 wherein the form of the hornexpansion is conical, exponential, hyperbolic, tractrix or a combinationthereof.
 3. The respirator of claim 1 wherein the airflow channel fromthe interior to the exterior of the module extends radially and axiallyoutwardly, then bends radially inwardly and axially outwardly through asmooth curve and then bends through a smooth curve axially outwardly,and does not reverse axial direction.
 4. The respirator of claim 1 andfurther comprising a drinking tube for selectively fluidly connecting amouthpiece projecting from the inner face of the module body to abeverage container adjacent the outer face of the module body.
 5. Therespirator of claim 1 wherein the outlet valve has a dome shape with acentral body and a generally conical skirt.
 6. The respirator accordingto claim 5 wherein the outlet valve conical skirt is slightly convexoutwardly toward the outer face of the module body.
 7. The respirator ofclaim 5 wherein the outlet valve further has convex shoulder hingebetween the central body and the conical skirt to toggle the outletvalve between an open position and a closed position.
 8. The respiratorof claim 7 wherein the convex shoulder hinge forms a channel that openstoward the inner face of the module body.
 9. The respirator according toclaim 1 wherein the airflow guide has a generally conical surface facingthe outer face of the module.
 10. The respirator according to claim 9wherein the airflow guide conical surface is concave.
 11. The respiratorof claim 9 wherein the airflow guide has a relatively flat bottomsurface facing the inner face of the module.
 12. The respirator of claim11 wherein an outer edge of the exhalation valve abuts the bottomsurface of the airflow guide when the exhalation valve is in the openposition.
 13. The respirator of claim 12 wherein the bottom surface ofthe airflow guide has relief channels to prevent sticking of theexhalation valve in the open position.
 14. The respirator of claim 1wherein the module further includes an electrical communication blockwith internal and external fittings for connecting a microphone in themask to a radio or amplifier carried by the mask user.
 15. A speechtransmitter and exhalation valve module adapted for mounting in anexhalation opening of a respirator and adapted to seal the exhalationopening to prevent inhalation of air therethrough and to open theexhalation opening to permit exhalation of air therethrough, the speechtransmitter and exhalation valve module comprising: a module body havingan inner face and an outer face; a central cavity for fluidly connectingthe inner face and the outer face; an airflow guide positioned withinthe central cavity, wherein the airflow guide forms with the module bodyan airflow channel in the form of a horn expansion contour duringexhalation; and an outlet valve adapted to close and fluidly seal thecentral cavity from the inner face during inhalation and to open duringexhalation, characterized in that: the airflow channel from the interiorto the exterior of the module extends radially and axially outwardly,then bends radially inwardly and axially outwardly through a smoothcurve and then bends through a smooth curve axially outwardly, and doesnot reverse axial direction.
 16. The module of claim 15 wherein the formof the horn expansion is conical, exponential, hyperbolic, tractrix or acombination thereof.
 17. The module of claim 15 wherein the outlet valvehas a dome shape with a central body and a generally conical skirt. 18.The module according to claim 17 wherein the outlet valve conical skirtis slightly convex outwardly toward the outer face of the module body.19. The module of claim 17 wherein the outlet valve further has convexshoulder hinge between the central body and the conical skirt to togglethe outlet valve between an open position and a closed position.
 20. Themodule of claim 19 wherein the convex shoulder hinge forms a channelthat opens toward the inner face of the module body.
 21. The module ofclaim 15 wherein the outlet valve forms a part of the airflow passagewhen it is in the open position.
 22. The module of claim 15 and furtherincluding an electrical communication port with internal and externalfittings for connecting a microphone in the mask to a poweredtransmitter carried by the mask user.
 23. The module according to claim15 wherein the airflow guide has a generally conical surface facing theouter face of the module.
 24. The module of claim 23 wherein the airflowguide has a relatively flat bottom surface facing the inner face of themodule.
 25. The module of claim 24 wherein an outer edge of theexhalation valve abuts the bottom surface of the airflow guide when theexhalation valve is in the open position.
 26. The module of claim 25wherein the bottom surface of the airflow guide has relief channels toprevent sticking of the exhalation valve in the open position.
 27. Arespirator comprising a facepiece defining an interior chamber forfiltered air and including at least one inhalation opening for passageof filtered air from the atmosphere to the interior chamber; at leastone exhalation opening for passage of air from the interior chamber tothe atmosphere; and a filtration canister removably mounted to thefacepiece and in fluid communication with the at least one inhalationopening for passage of purified atmospheric air to the facepieceinterior chamber; a self-sealing valve mounted in the at least oneinhalation opening and adapted to seal the at least one inhalationopening to prevent inhalation of air therethrough when the filtrationcanister is removed from the facepiece and to open the at least oneinhalation opening to permit inhalation of air therethrough when thefilter canister is mounted to the facepiece; and a speech transmitterand exhalation valve module mounted in the at least one exhalationopening and adapted to seal the at least one exhalation opening toprevent inhalation of air therethrough and to open the at least oneexhalation opening to permit exhalation of air therethrough, the speechtransmitter and exhalation valve module comprising: a module body havingan inner face, an outer face and an outer wall; a airflow cavity definedby an inner side wall of the module body and extending between openingsin the inner and outer faces of the module for fluidly connecting theinner face and the outer face; an airflow guide positioned within thecentral cavity; an outlet valve, mounted to the module body and in theairflow cavity, and adapted to close and fluidly seal the airflow cavityduring inhalation and to open during exhalation, and wherein inner sidewall of the module forms with the airflow guide an airflow channel inthe form of a horn expansion contour during exhalation when the outletvalve is in an open position; characterized in that: an electricalcommunication block with internal and external fittings for connecting amicrophone in the mask to a radio or amplifier carried by the mask user.28. A respirator comprising a facepiece defining an interior chamber forfiltered air and including at least one inhalation opening for passageof filtered air from the atmosphere to the interior chamber; at leastone exhalation opening for passage of air from the interior chamber tothe atmosphere; and a filtration canister removably mounted to thefacepiece and in fluid communication with the at least one inhalationopening for passage of purified atmospheric air to the facepieceinterior chamber; a self-sealing valve mounted in the at least oneinhalation opening and adapted to seal the at least one inhalationopening to prevent inhalation of air therethrough when the filtrationcanister is removed from the facepiece and to open the at least oneinhalation opening to permit inhalation of air therethrough when thefilter canister is mounted to the facepiece; and a speech transmitterand exhalation valve module mounted in the at least one exhalationopening and adapted to seal the at least one exhalation opening toprevent inhalation of air therethrough and to open the at least oneexhalation opening to permit exhalation of air therethrough, the speechtransmitter and exhalation valve module comprising: a module body havingan inner face, an outer face and an outer wall; a airflow cavity definedby an inner side wall of the module body and extending between openingsin the inner and outer faces of the module for fluidly connecting theinner face and the outer face; an airflow guide positioned within thecentral cavity; and an outlet valve, mounted to the module body and inthe airflow cavity, and adapted to close and fluidly seal the airflowcavity during inhalation and to open during exhalation, characterized inthat the outlet valve has a dome shape with a central body and agenerally conical skirt.
 29. The respirator according to claim 28wherein the outlet valve conical skirt is slightly convex outwardlytoward the outer face of the module body.
 30. The respirator of claim 27wherein the outlet valve further has convex shoulder hinge between thecentral body and the conical skirt to toggle the outlet valve between anopen position and a closed position.
 31. The respirator of claim 30wherein the convex shoulder hinge forms a channel that opens toward theinner face of the module body.